The present invention relates to devices, systems and methods that aid in the performance of spinal revision surgery in which previously implanted spinal fixation instrumentation is extended to additional vertebrae. More particularly, the invention provides coupling systems and methods that allow for a first, implanted spinal fixation element to be coupled to a second spinal fixation element while leaving the first element in place.
The use of spinal fixation instrumentation to align and/or fix a desired relationship between adjacent vertebral bodies is well established. Such instrumentation typically includes a spinal fixation element, such as a relatively rigid plate or a rod, that is coupled to adjacent vertebrae by attaching the element to pedicle screws which have been inserted into the patient""s vertebrae. Once installed, the spinal fixation instrumentation holds the vertebrae in a desired spatial relationship, either until desired healing or spinal fusion has taken place, or for some longer period of time.
While use of such spinal fixation instrumentation is effective in treating a number of spinal disorders and traumas, it sometimes becomes necessary to extend the instrumentation from the vertebrae being treated to one or more additional adjacent vertebrae. This can be accomplished by removing the existing spinal fixation element (in particular, removing the rod(s) or plate(s) that fix the alignment of the previously treated vertebrae), and replacing it with a new element configured to treat all of the vertebrae needing treatment. Spinal fixation elements, however, are carefully shaped and placed to result in a desired alignment. Accordingly, removal, or even sometimes movement, of a spinal fixation element can result in significant effort by a surgeon to realign the previously aligned vertebrae and instrumentation, in addition to treating additional vertebrae. In addition, it is preferable not to remove implanted pedicle screws as the replacement of such screws in the patient""s vertebrae can result in the removal of additional bone material from the patient""s spine.
Accordingly, there is a need for a coupling system and method for extending previously implanted spinal instrumentation to additional vertebrae without removing the existing instrumentation. In particular, coupling systems and methods that can couple a second spinal fixation element to a first, implanted spinal fixation element while leaving the first element in place would simplify revision surgery for the surgeon, and likely provide many benefits for the patient as well.
The present invention solves the described problems in the art and others by providing a coupler for connecting a first, slotted, implanted spinal fixation element to a second spinal fixation element. In a first aspect, the invention includes a coupler having a post and a head disposed on a distal end of the post. The head of the coupler has a width shorter than a width of a slot in the first, slotted, implanted spinal fixation element, and a length longer than the width of the slot in the first, slotted, implanted spinal fixation element. The coupler with a head so configured can be placed in a first orientation so that the head passes through the slot in the first, slotted, implanted spinal fixation element, and then can be placed in a second orientation wherein the head is trapped beneath the first, slotted, implanted spinal fixation element while the post having a connecting element extends through the slot. In this way, a coupler can be provided for connecting a second spinal fixation element without removing the first, slotted, implanted spinal fixation element.
In a further aspect of the invention, a system for extending a first, implanted spinal fixation element to one or more additional adjacent vertebrae while leaving the first, implanted spinal fixation element in place is provided. The system includes a second spinal fixation element, a coupler, and a second spinal fixation element attachment member. The coupler has a connecting member and a head disposed on a distal end of the connecting member for holding the coupler to the first, implanted spinal fixation element. The second spinal fixation element attachment member has a coupler attaching portion for attaching to the connecting member of the coupler and a second spinal fixation element attaching portion. In this system, when the coupler is assembled to the first, implanted spinal fixation element, the second spinal fixation element attachment member is assembled to the coupler, and the second spinal fixation element is assembled to the second spinal fixation element; the system extends spinal treatment from the first, implanted spinal fixation element to one or more adjacent vertebrae while leaving the first, implanted spinal fixation element in place.
In one embodiment of this aspect of the invention, the first, implanted spinal fixation element is slotted and the head of the coupler is configured to hold the coupler to a slot on the first, implanted spinal fixation element. In this embodiment, the head has a width shorter than a width of the slot in the first, implanted spinal fixation element, and a length longer than the width of the slot in the first, implanted spinal fixation element. When this coupler is placed in a first orientation, the head passes through the slot, and when the coupler is then placed in a second orientation, the head is trapped beneath the first, implanted spinal fixation element while the connecting member extends through the slot.
In a further embodiment of this aspect of the invention, the second spinal fixation element can be a spinal fixation rod and the second spinal fixation element attaching portion of the second spinal fixation element attachment member can define a bore for accepting and attaching the spinal fixation rod.
In a further aspect of the invention, a method is provided for extending a first, implanted spinal fixation element to one or more additional adjacent vertebrae while leaving the first, implanted spinal fixation element in place. The method includes assembling a coupler having a connecting member and a head disposed on a distal end of the connecting member for holding the coupler to the first, implanted spinal fixation element; assembling a second spinal fixation element attachment member having a coupler attaching portion for attaching to the connecting member of the coupler and a second spinal fixation element attaching portion to the coupler; assembling a second spinal fixation element to the second spinal fixation element attachment member; and fixing the second spinal fixation element to the one or more additional adjacent vertebrae. Each of the steps in this method can be performed while the first, implanted spinal fixation element is left in place.
In one embodiment of this aspect of the invention, the first, implanted spinal fixation element is slotted and the head of the coupler is configured to hold the coupler to a slot on the first, implanted spinal fixation element. The head has a width shorter than a width of the slot in the first, implanted spinal fixation element, and a length longer than the width of the slot in the first, implanted spinal fixation element. The step of assembling the coupler to the first, implanted spinal fixation element can thus include placing the coupler in a first orientation wherein the head passes through the slot, passing the head through the slot, and placing the coupler in a second orientation wherein the head is trapped beneath the first, implanted spinal fixation element while the connecting member extends through the slot.
In a further embodiment of this aspect of the invention, the second spinal fixation element is a spinal fixation rod and the second spinal fixation element attaching portion of the second spinal fixation element attachment member defines a bore for accepting and attaching the spinal fixation rod. In this embodiment, the step of assembling the second spinal fixation element to the to the second spinal fixation element attachment member includes fixing the rod within the bore.